Disk vacuum power interrupter

ABSTRACT

A vacuum circuit interrupter comprising a cylindrical envelope having upper and lower ceramic or glass closure insulator plates through which axially aligned relatively movable contact rods having impedance means comprising a pair of relatively shallow cylindrical metallic shields that are concentrically affixed to associated ones of the contact rods.

D United States Patent [191 [111 3,727,018 Wesoloski et a]. 5] Apr. 10,1973 [54] DISK VACUUM POWER INTERRUPTER 3,280,286 10/1966 Ranheim ..200144 B [75] Inventors: Henry J. wesoloski, Cohasset; 3,366,825 l/l968Lafferty ..200/144 B X gust Arns, Jr., North Easton, both f Mass PrimaryExaminer-Robert S. Macon Att R b rtC. J t [73] Assignee: Allis-ChalmersCorporation, Mil- Omey o e ones 6 a1 waukee, Wis. 57] ABSTRACT [22]Filed: Sept. 16, 1971 A vacuum circuit interrupter comprising acylindrical PP 181,095 envelope having upper and lower ceramic or glassclosure insulator plates through which axially aligned [52] US. Cl...200/ 144 B relatively movable Contact rods having impedance [51] Int.Cl. ..H01h 33/66 means comprising a pair of relatively shallow cylindri-[58] Field of Search ..200/ 144 B cal metallic shields that areconcentrically affixed to associated ones of the contact rods. [56]References Cited 5 Claim, 3 Drawing Figures UNITED STATES PATENTS3,087,034 4/1963 Beers et a]. ..200/144 BACKGROUND OF THE INVENTION Thisinvention relates to circuit interrupters and more particularly tointerrupters of the vacuum type which include an evacuated housing, orenvelope, in which movable circuit contact rods are arranged for makeand break operations. The operation of the contacts in the interruptersin interrupting a circuit is accompanied by arcing wherein relativelyhigh temperatures are experienced. The high temperature causes thecontact metal to vaporize which is a good conductor of electricity andtends to increase the current flow within the envelope. Also, themetallic particles in the vapor are dispersed in all directions fusingon the interior surface of the envelope and impairs the operation of theinterrupter. To overcome the difficulties the envelopes have been madeof glass or a ceramic material. With ceramic or glass lined metallicenvelopes, the incorporation of the interior arc shields is extremelydifficult in view of the complicated mounting arrangements required.

SUMMARY OF THE INVENTION In accordance with the present invention, thereis provided a circuit interrupter wherein the envelope is constructed ofmetallic material having glass or ceramic insulating end closure platesthrough which relatively movable contact rods extended, being insulatedfrom the envelope or body by the glass insulating end closure plates.Each contact rod is provided with an arc shield that is fixedly securedto an associated one of the contact rods in a manner to be relativelymovable with respect to each other upon the relative movement of thecontact rods themselves.

One object of the present invention is to provide a compact, rigid andreliable vacuum circuit interrupter capable of accommodating largecontact rods or studs, which are capable of carrying and interruptinghigher currents,

Another object of this invention is to provide a compact, rigid andreliable vacuum circuit interrupter comprising relatively fewer partsthereby having fewer seams or joints wherein leakage can occur.

Still another object of this invention is to provide a compact, rigidand reliable vacuum circuit interrupter which includes a compact arcshield fixedly attached to each of the associated contacts, one of whichmay be movable and the other a fixed contact.

Yet another object of this invention is to provide a compact, rigid andreliable vacuum circuit interrupter having a circular metallic bodyportion, the ends of which are closed by glass insulating end plates.

Other objects and advantages of the invention will hereinafter appear.

DRAWING FIG. 1 is a view taken through the interrupter being partly invertical section and partly in elevation showing the assembly as itappears when the contact rods are in closed position.

FIG. 2 is an end view of one of the pair of contact inserts shown inFIG. 1; and

FIG. 3 is a view in section taken in a plane represented by the line3--3 on FIG. 2.

DESCRIPTION In the drawing, the numeral 10 designates a high voltagevacuum type electrical circuit interrupter or switch. The interrupter 10comprises an envelope 1] formed as an upper and lower cup 12 and 14,respectively. The cups l2 and 14 are identical in form and each has aninwardly extending flange portion 16 and 17, the inner edge of which isrolled backwardly so as to face radially outwardly. The roller portion18 and 19 of the flanges operate as reinforcing elements which givesadditional strength andrigidity to their associated cups, and byeliminating sharp corners serve the additional function of reducing theelectric field gradient.

The lower cup 14 is provided with an insulator and closure plate 21which is preferably glass but may be a ceramic material if so desired. Acircular opening 22 is formed in the glass end plate 21 with its axisbeing coaxial with the axis of the cup 14. Inserted into the opening 22of the end plate 21 is a metallic bushing 26 having an axial bore 27 andan outwardly extending radial supporting flange 28. The externaldiameter of the hub of the bushing 26 is such that a snug fit isobtained between the bushing and the end plate 21.

With the bushing 27 assembled to the glass end plate 21, the plate 21 isinserted into position in the cup 14. The diameter of the end plate 21is such that a snug fit of the plate in its sealed position in the endplate is effected. In inserting the glass end plate into the cup care istaken to insure that mechanical stresses are not developed between theplate and the cup.

With the cup 14 and closure plate 21 and bushing 26 assembled the entireassembly is subjected to a bonding process so that a leak free bond isobtained between the contacting outer surface of the glass end plate andthe supporting inner surface of the cup flange 17 and also between theperipheral edge of the glass end plate and the adjacent inner surface ofthe cup 14; likewise a leak free bond is obtained between the externalsurface of the hub of bushing 26 and the adjacent contacting surface ofthe wall of the opening 22 as well as the contacting surfaces of theglass plate and the radial flange portion 28 of the bushing 26.

The cup 14 and bushing 26 are preferably of an ironnickel-cobalt alloyhaving a coefficient of thermal expansion which closely matches that ofthe glass or ceramic end plate 21. A metallic alloy which is preferred,is a commercially available product manufactured by the CarborundumCompany and presently sold under the trademark KOVAR.

A contact rod or stud 31 of oxygen-free, high-conductivity copper isdisposed within the bore 27 of the bushing 26 and is of a diameter thatprovides a smooth noninterfering movable fit therein so as to providefor free axial movement of the contact rod in the bushing. At its inneror upper end, the contact rod 31 is provided with a large diametercopper contact 32 which is secured to the end of contact rod formovement therewith as by being brazed thereto. The large diametercontact rod 32 is provided with a flat upper circular surface 33 theperipheral edge of which is contingent to a peripheral beveled surface34 that slopes downwardly to the peripheral edge of the contact.

As shown in FIGS. 2 and 3 the contact 32 is provided with a plurality ofslots 35 which divide the contact into discrete segments 36. The slots35 are shown as being generally of a spiral configuration and areconstructed and arranged so as to overlap one another. An arc initiatedon one of the segments 36 is driven outwardly dueto the magnetic effectresulting from the looped path in accordance with well known principlesand is also caused to rotate. As the arc rotates, it is forced to jumpfrom segment to segment across an intervening slot 35. The tendency ofan arc to hang on at the edge of a slot as its jumps from segment tosegment is overcome by filling the slots 35 with a high resistancematerial 37, such as nickel or iron. The high resistance material 37 isinserted into the slots 35 so that the material is flush with thesurface 33 of the contact.

Disposed within an axial recess 38 formed in the upwardly facing flatsurface 33 of the contact 32 is a circular contact insert 39 which issecured in position as by brazing. The insert 39 is a metallic materialother than pure copper, and preferably of a copper alloy which has goodconductivity evidencing a high resistance to welding in a vacuumenvironment.

Mounted on the contact rod 31 in coaxial relationship is a disk areshield 41 which in cross-section presents a pie-shaped configuration.The are shield 41 is fixedly secured to the contact rod 31 so as to moveaxially with the rodand is positioned thereon so that its peripheraledge 42 is located in a horizontal plane which is spaced from thehorizontal plane in which the bottom surface of the contact 32 isdisposed. The diameter of the shield is of a dimension to insure thatthe peripheral edge 42 of the shield extends well beyond the peripheraledge of the contact rod 31. The construction and arrangement of theshield 41 is such wherein a line of sight line, represented by thebroken line 43, is tangent to the peripheral edge 42 of the shield 41and the upper peripheral edge 44 of a copper contact 96 but does notintersect the surface of the end plate 21. With this arrangement anymetallic particles that may be impelled downwardly toward the insulatorand plate 21 will be deflected and/orintercepted so that such metallicparticles cannot deposit on the insulator end plate 21 to form aconductive path.

The contact rod extends downwardly through the .axial opening 27 in thebushing 26 and through a prounder surface of the flange 28 of thebushing .26. A

sealing washer 52 is mounted about the contact rod 31 and is securedthereto for axial movement with the rod. The depending end of thebellows 51 is secured in a sealed constructional arrangement to thesealing washer 52. The bellows 51 is of a length so as to expanddownwardly without strain upon a full operating stroke of thecontact rod31. The extending end of the contact rod 31 and the bellows 51 aredisposed within a tubular mounting collar 56. At its upper end adjacentto the bushing 26 the'collar 56 encompasses the flange 28 of the bushing26 being fixedly and rigidly secured thereto. The lower depending end ofthe mounting collar is provided with a circular bolt ring 57 having aplurality of bolt holes 58, two of which are shown; the ring 57 beingwelded in position to the outer surface of the mounting collar 56. Formounting the interrupter to a support (not shown) a base plate 61 isprovided with bolt holes 62 which are axially aligned with associatedones of the bolt holes 58 formed in the ring 57.

The extending lower end of the contact rod 31 is threaded, as at 66, andextends through an opening 67 formed in the base plate 61. As shown inthe drawing, the threaded end of the contact rod 31 is provided with anaxial extending flat surface 68 that cooperates with a flat wall surface69 of a semicircular lower portion 71 of the opening 67. With thearrangement disclosed free i axial movement of the contact rod 31 ispermitted but the rod 31 is prevented from rotating by operation of theflat surface 68 on the rod 31 cooperating with the flat wall surface 69of the lower portion of the opening '67. Thus, the danger ofinadvertently opening the various sealed joints of the assembly such asbetween the sealing washer 52 and stud 31, or the lower end of thebellows 51 and the sealing washer 52, or the upper end of the bellows 51and the bushing 26 is eliminated.

In forming the flat surface 68 on the lower depending end 66 of thecontact rod 31 a shoulder 72 is constructed. The portion of the contactrod 31 wherein the shoulder 72 is located is disposed within thecircular upper portion 73 of the opening 67. The depth of the circularportion 73 is such that the shoulder 72 on the contact rod 31 willengage a shoulder 74 adjacent to the flat wall surface 69 of thesemicircular lower portion 71 of the opening 67. This arrangement actsasa positive stop and effectively establishes the maximum axial travel ina downwardly or outwardly direction permitted to the contact rod 31. Inthis manner, inadvertent over-travel of the contact rod in a downwardseparating stroke cannot occur thereby eliminating the dangers ofaccidentally damaging the assemblies associated with the lower envelopecup unit 14 is avoided.

The upper cup 12 assembly is similar to the lower cup assembly. Asshown, the upper cup 12 is provided with an insulator end closure plate81 similar to the end plate 21 associated with the cup 14. A circularopening 82 having its axis coinciding with the axis of the end plate 81,is formed in the end plate. The diameter of the end plate 81 isdimensioned so that upon assembly of the end plate into a positionabutting the flange 16 of the cup 12, a snug fit between the end plateand cup is obtained.

Inserted into the axial opening 82 of the end plate 81 is a bushing 83having an axial opening 84 and provided a radial outwardly extendingflange 86. in assembled condition the axes of the bushing 83, end plate81 and cup 12 are constructed and arranged so as to coincide. Assemblyof the bushing 83 into'position in the end plate 81 is effected prior toeffecting the bonding of the end plate to the cup 12. Thus, when bondingis effe'cted, the joint between the periphery of the end plate andcontacting interior surface of the wall of the cup 12, as well as thejoint between the contacting surfaces of the glass end plate and theflange 16 are sealed to provide a leak-free joint. Likewise, the jointbetween wall of the opening 82 andgthe exterior contacting peripheralsurface of the bushing hub and the contacting surfaces of the glass endplate with the top surface of the flange 86 will also be sealed toprovide a leak free joint.

The cup 12 and bushing 83 are of the same type of iron-nickel-cobaltalloy as set forth for the cup 14 and bushing 26. Thus, all of themetallic parts of theenvelope will have a similar thermal coefficient ofexpansion as well as the same electrical characteristics.

The bushing 83 receives the reduced portion 91 of an upper fixed contactrod 92. A shoulder 93 formed by the reduced portion 91 abuts the bushing83 to give positive location to the contact rod 92 so that the axis ofthe rod coincides with axis of the bushing 83. As stated, the rod 92 isa fixed or stationary contact member and is secured in the bushing 83 bybeing brazed therein, the braze being carried about the entirecircumference of the rod both at the lower and upper end surfaces of thebushing as indicated. In this manner the rod 92 is fixedly secured inthe bushing 83 and the joint at the shoulder 93 is sealed, as well as,the joint at the upper end face of the bushing is also sealed to provideleak-free joints.

A large diameter copper contact 96 identical in construction andarrangement to the lower contact 32 is secured to lower depending end ofthe rod 92. A contact insert 97 is brazed in position in an axial recess98 formed in the contact 96. The contact insert 97 is identical to thecontact insert 39 so that when the interrupter is in conductingcondition the upper and lower contact inserts 97 and 39 conductivelyengage. In this manner, since the inserts are of a metallic materialother than pure copper, and preferably of a copper alloy which has goodconductivity and evidencing a high resistance to welding, welding of thecontacts will not occur.

Immediately above the contact 96 there is provided an arc shield 99. Theshield 99 is identical to the shield 41 and is mounted about the rod 92being fixed in position thereon as by being brazed. The diameter of theshield 99 is such that a line of sight line, represented by the brokenline 101, is tangent to the peripheral edge 102 of the shield 99 and thelower peripheral edge 103 of the lower contact 32 but does not intersectthe surface of the end plate 81. In this manner, the shield 99 willdeflect or intercept any metallic particles that are impelled upwardstowards the insulator end plate 81. Thus, the likelihood of a layer ofmetallic particles coating the surface of the insulator plate 81 andproviding a conductive path is eliminated.

The two cups l2 and 14 after bonding and assembly of the associatedelements therewith are welded or otherwise secured together. To thisend, the lower cup 14 is provided with an outwardly extending radialflange 106 and the upper cup 12 is providing with a similar radialoutwardly extending flange 107. The flanges 106 and 107 arecomplementary and are disposed in abutting relationship, thereby forminga stable supporting base which may be easily sealed and welded torigidly couple the two cup members together with a leak-free joint.

With the two cup assemblies secured together in sealed relationship, theinterior chamber 110 of the interrupter 10 is evacuated to provide avacuum in the chamber. To this end, a vertical passage 111 is formed inthe contact rod 92 which has communication with a horizontal passage 112drilled through the rod 92. The outer end of the passage 111 is providedwith a tube 114 which is secured in sealed relationship in the outer endof the passage. When the chamber 110 is evacuated the tube 114 ispinched off to seal the evacuated chamber.

The circuit interrupter set forth presents a compact, rigid and reliabledevice which is capable of carrying and interrupting a higher currentthan heretofore possible with comparable sized prior art interrupters.It is also apparent that the manufacture and assembly of the devicedisclosed is simplified thereby offering a material reduction in thecost of manufacture. Also, the servicing of the device is facilitatedfor the device may be parted at the joint juncture of the two cupmembers 12 and 14 to thereby separate the device into its two basic unitcomponents.

The invention is described in detail in a particular form and it will beappreciated that modification can be made without departing from spiritand scope of the illustrated embodiment of the invention set forth anddescribed.

We claim:

1. In a vacuum circuit interrupter;

an envelope comprising identical first and second metallic units eachconstructed and arranged as metallic rings having radial inwardlyextending flanges at one end and radial outwardly extending flanges atthe opposite ends, said units being joined with their outwardlyextending flanges in abutting sealed relationship;

a first glass insulator flat end plate closure disposed in'the free endof said first unit in bonded sealed engagement with the radial inwardlyextending flange thereof;

second glass insulator flat end plate closure disposed in the free endof said second unit in a bonded sealed engagement with the radialinwardly extending flange thereof; first contact rod extending into saidfirst unit through an axial opening in said first glass insulator endplate closure in sealed relationship therewith;

a second contact rod extending into said second unit through an axialopening in said second glass insulator end plate closure;

means operable to effect a seal between said second contact rod and theaxial opening in said second glass insulator end plate closure throughwhich said contact rod extends in a manner to permit said second contactrod to move axially in a contact make-or-break path of travel.

2. A vacuum circuit interrupter according to claim 12 including meansoperable to engage said second contact rod for limiting the axialmovement thereof in a circuit interrupting direction of movement.

3. A vacuum circuit interrupter according to claim 13 including meansoperable to prevent rotation of said movable second contact rod withoutinterfering with the axial movement thereof.

4. A vacuum circuit interrupter according to claim 14 including meanscarried by said interrupter for mounting said interrupter to anassociated structure.

5. In a vacuum circuit interrupter;

a rigid envelope comprising identicalfirst and second metallic unitseach having both ends open, said sealing means to seal the space betweensaid first contact rod and the opening in said first end plate closurethrough which said first contact rod extends;

- a second insulating end closure secured in sealed relationshipin theopen free end of said second envelope unit, said first insulating endplate closure having an axial opening therein;

a second contact rod extending into said second unit through theaxial'opening in said second end plate

1. In a vacuum circuit interrupter; an envelope comprising identicalfirst and second metallic units each constructed and arranged asmetallic rings having radial inwardly extending flanges at one end andradial outwardly extending flanges at the opposite ends, said unitsbeing joined with their outwardly extending flanges in abutting sealedrelationship; a first glass insulator flat end plate closure disposed inthe free end of said first unit in bonded sealed engagement with theradial inwardly extending flange thereof; a second glass insulator flatend plate closure disposed in the free end of said second unit in bondedsealed engagement with the radial inwardly extending flange thereof; afirst contact rod extending into said first unit through an axialopening in said first glass insulator end plate closure in sealedrelationship therewith; a second contact rod extending into said secondunit through an axial opening in said second glass insulator end plateclosure; means operable to effect a seal between said second contact rodand the axial opening in said second glass insulator end plate closurethrough which said contact rod extends in a manner to permit said secondcontact rod to move axially in a contact make-or-break path of travel.2. A vacuum circuit interrupter according to claim 12 including meansoperable to engage said second contact rod for limiting the axialmovement thereof in a circuit interrupting direction of movement.
 3. Avacuum circuit interrupter according to claim 13 including meansoperable to prevent rotation of said movable second contact rod withoutinterfering with the axial movement thereof.
 4. A vacuum circuitinterrupter according to claim 14 incLuding means carried by saidinterrupter for mounting said interrupter to an associated structure. 5.In a vacuum circuit interrupter; a rigid envelope comprising identicalfirst and second metallic units each having both ends open, said unitsbeing secured to each other in coaxial sealed relationship; a firstinsulating flat end plate closure secured in sealed relationship in theopen free end of said first envelope unit, said first insulating endplate closure having an axial opening therein; a first contact rodextending into said first envelope unit through the axial opening insaid first end plate closure; sealing means to seal the space betweensaid first contact rod and the opening in said first end plate closurethrough which said first contact rod extends; a second insulating endclosure secured in sealed relationship in the open free end of saidsecond envelope unit, said first insulating end plate closure having anaxial opening therein; a second contact rod extending into said secondunit through the axial opening in said second end plate closure; anaxial deflectable bellows operatively arranged to seal the space betweensaid second contact rod and the opening in said second end plate closurethrough which said second contact rod extends in a manner to permit saidsecond contact rod to move axially relative to said first contact rod incontact make-and-break operations.